Tone-producing means.



M. L. SEVERY & G. B. SINCLAIR.

TONE PRODUCING MEANS.

APPLICATION FILED AUG. 8 I914.

19,199,934. Patented Oct. 3,1916

2 SHEETS-SHEET I.

M. L. SEVERY & G. B. SINCLAIR.

TONE PRODUCING MEANS.

APPLICATION FILED AUG.B, 1914.

Patented Oct. 3,1916.

2 SHEETS-SHEET 2 UNITED STATES PATENT OFFICE,

MELVIN L. SEVERY, 0F ARLINGTON HEIGHTS, MASSACHUSETTS, AND GEORGE B. SINCLAIR, OF GEORGETOWN, MAINE.

TQNE-IPROD'UCING MEANS.

Specification of Letters Patent.

Patented Oct. 3, 1916.

Original application filed February 20,1910, Serial No. 545,962. Patent No. 1,137,544, dated April 27, 1915. Divided and this application filed August 8, 1914. Serial No. 855,885.

- tion of musical tones of relatively incommensurate vibrations; and the production of tones of easily changeable timbre.

The present application is a division of our application Serial No. 545,962, which eventuated in Patent No.- 1,137,544, dated Apr. 27, 1915 to which reference may be made for any features or details not found herein pertaining to the general or broad principles involved but not claimed herein.

In the accompanying drawings: Figure 1 is an elevation ofmeans for the production of musical tones in accordance with our inelectromagnet 4, and by the relay 5 controlling the currents from sources 6 and 7. This means of rotating the shaft at uniform speed is illustrative merely, and may be replaced by any other motor and synchronizing device capable of giving the perfect regulation of speed essential to this class of work. i

Upon the shaft 1 we mount one or more rotors 10, formed with teeth,lugs or projections 27, which upon rotation of the shaft travel past and in proximity to inwardly projecting lugs or poles of an encircling stator 21". This stator is provided with coils or wmdings 89, in which are induced alternating currents as the projections of the rotor approach and recede from those of the stator. These alternating current pulsations are led by suitable conductors to an electromagnet 22, the conductors being electrically connected with the terminals of the coils of the magnet.

Facing a pole of the electromagnet 22 is a string 23, a diaphragm 24, or other body adapted through alternate attraction and release by the magnet, to be thrown into sonorous vibration. In order to cause non-at" tractive intervals for the recession of the sonorous or vibrating body, the magnet 22 is polarized. This may be eifected by ei'nploy ing an extended magnet core, and winding the same with a second coil 25 receiving continuous current from asuitable source 26. It will be seen that under this construction when the coils 22 and 25 receive currents of like polarity, the core will be strongly magnetized and strongly attract the sonorous or vibrating body within its field; but when during the opposite phase of each alternation the two currents are of unlike polarity, the polarity of the core is neutralizedand the sonorous body is accordingly released. Consequently, such sonorous body will be alternately attracted and released, its own resilience or tendency to return to normal position causing the swing or movement outward or away from the magnet pole.

'As each movement of a tooth or projection 27 of the rotor past a pole-piece of the stator energizes the electromagnet 22 connected therewith, the strength of energization and consequently the loudness of the sonorous vibrations caused thereby, can be multiplied by increasing the number of teeth and pole pieces simultaneously acting to energize such electromagnet. To thus increase the pole pieces it is of course necessary to properly space them so that the angular distances between them shall exactly equal or be some multiple of that between the teeth. So long as there is a non-fractional number of said teeth about the rotor heads, it is easily practicable thus to multiply the pole pieces, but whenever, as in the majority of the strings of a musical instrument, it is necessary to provide pulsations for sonorous bodies which vibrate incommensuratelv with respect to others, and mcommensurate rotors are accordingly used, it is impossible thusto surround the entire rotor withpole pieces. lVe have therefore'devised means for providing one half the rotor with simultaneously effective pole pieces, and this. consti-. tutes the specific subject-matter of the pres ent application, divided out 'of the parent application, Serial No. 545,962, now Patent No. 1,137,544.. i

' As shown in Figs. 2 'and 8, a rotor head 10 is formed with teeth 27, one or more spaces'between which are abnormal as at 28, which space absorbs the fractional tooth that would otherwise occur thereat. Referring to Fig. 2, it will be seen that about such rotor head 10 is located a series of pole pieces equal in number to the teeth 27, and

with angular spaces between them, one, of.

the latter, 29, being abnormal in measurement or extent. As is evident on inspection,

a number of the teeth andpole pieces will not meet simultaneously with others. We

therefore provide an automatically actuated switching means for cutting out of circuit to. the electromagnet 22 the windings of the pole pieces which are not met by the teeth at the same instant as are the others. This is'done as follows: In continuousg contact with the shaft 1 of therotor is a brush 32 joined by a wire 33' to the electromagnet 22.

Fixed on said shaft is a semicircular contact piece 34in circuit therewith. At .diametrlcally opposite sides of the shaft, and in contact with said contact plece 34 when the-latter passes them, are two brushes 36, 37, the brush 36 being joined, by wire 38 toone terminal coil 39 of the set of tandem coils 39 wound about the pole pieces 21, while the opposite terminal coil 39 is joined'by a. wire 40 to the electromagnet 22. The brush 37 is joined by wire 41 to the terminal coil 42* of the tandem coils 42, and the opposite terminal coil 42 is joined by wire 43 to the wire 40, and by the latter to said electromagnet. by the abnormal space'28 will always be cut out from the circuit to the electromagnet 22,

while those pole pieces not thus confronted and constituting the other half or group,

will be in such circuit throughout every rev- Hence the pole pieces confronted cutting out. more orless of the pole pieces as )by shifting the brushes 44 of the wires 40,

43 toward the coils '39 and 42,"respectively.

- In Figs. 2 and-3 for 'thesake of clearness we have shown but one rotor on eachshaft with its opposing stator, but it is manifest that in a musical instrument having a number of musical pitches, .We should use a plu- I rality of these rotors and stators, and each i shaft 1 would preferably carry av group of rotors. In most instrumentsjthere would be several of these groups moving at speeds commensurate. withone another. It is clear, therefore, that if commensurate speeds are to produce trains of timed current-impulses, the said trains being incommensurate with one another, there must be at least one. break in some of the cycles of impulses. For example, if the speed of the generating device be suited, say, 'to- C, and C be without fractional provision, as it usually would be, then C# revolving either fixedly o'r commensurate with C, would require fractional provision. VVe have ascertained by years of experimentation that this fractional provision does not sensibly-impair the value of the resulting current waves for use in selective apparatus, nor does it cause. the resulting tone of tuned sonorous bodies-to lose'their full timbre characteristics.

While the production of musical tones is a prominent and perhaps the primary purpose of this invention, it is by no means restricted to such use, but is of somewhat wide respond with said teeth, said rotor and stator being provided with suitable means including coils for enabling them to generate and transmit to said electromagnet current alternations from either half of said pole pieces;

and switching means whereby the current alternations are generated and transmitted from each half ofsaid pole pieces when said abnormal space is opposing the other half.

2. A tone-producing instrument comprising a sonorous body; an electromagnet for its vibration; a uniformly rotated rotor having a head provided with equally spaced teeth with the exception that at one point is a space abnormal in length; a stator having pole pieces equally spaced to correspond to said equally spaced teeth; and windings on said pole pieces in circuit with said electromagnet, means being provided for cutting out of circuit temporarily the windings of the pole pieces which fail to correspond with teeth on said rotor.

3. In combination with an electromagnet and a body to be vibrated thereby, a rotor having teeth uniformly spaced throughout the major portion of its circumference butunequally spaced at a point therein; a stator having pole pieces facing the teeth of said rotor, said rotor and stator being provided with suitable means including coils for enabling them to generate and transmit 'to said electromagnet current alternations from said pole pieces; and switching means whereby the current alternations are generated and transmitted during rotation of the rotor, from pole pieces other than those opposing the abnormal space.

4. In combination with an electromagnet and a body to be vibrated thereby, a rotor having teeth uniformly spaced throughout the major portion of its circumference but unequally spaced at a, point therein; a stator having pole pieces facing the teeth of said rotor and likewise equally spaced through the major portion of the series but unequally spaced at a point or points therein; means including coils for enabling said rotor and stator to generate and transmit to said electromagnet current alternations from said pole pieces; and switching means whereby the current alternations are generated and transmitted during rotation of the rotor from pole pieces other than those opposing the abnormal space, 5. In combination with a body to be vibrated, an electromagnet for effecting its vibration; a uniformly rotatable rotor having a head provided with teeth equally spaced throughout the major portion of the series but unequally spaced at a point therein; a stator having pole pieces likewise equally spaced throughout the major portion of the series but unequally spaced at a point or points therein; windings on said pole pieces in circuit with said electromagnet; and means for cutting out of circuit temporarily the windings of those pole pieces which at the instant are not faced by or opposed to equally spaced teeth of the rotor. In testimony whereof we have signed our names to this specification in the presence of two subscribing witnesses.

MELVIN L. SEVERY. GEORGE B. SINCLAIR.

Witnesses:

EDWARD S. CRocKE'rT, EMMA F. DUNLOP. 

